1：Experimental Design and Method Selection:

The study employs a one-pot reflux method using edible carrot as a carbon source and trisodium phosphate (TSP) as a catalyst to synthesize carbon dots (CDs). The rationale is to provide a simple, cost-effective, and environmentally friendly alternative to existing methods that require sophisticated equipment.

2：Sample Selection and Data Sources:

Edible carrot was procured from a local supermarket. Other chemicals like trisodium phosphate, sodium borohydride, silver nitrate, and gold chloride were purchased from commercial suppliers (Merck, Fisher Scientific, Alfa Aesar). Double distilled water was used throughout.

3：List of Experimental Equipment and Materials:

Equipment includes a round bottom flask, condenser, laboratory heating mantle, UV lamp, Jasco-FP8200 spectrofluorimeter, Thermo Scientific Evolution 201 spectrophotometer, JEOL-JEM 1011 TEM, Perkin Elmer spectrum-one FTIR instrument, Bruker 300 MHz NMR instrument, Thermofisher scientific Kα XPS instrument, Nikon Eclipse fluorescence microscope, FEI-Tecnai G2 20 S-TWIN HRTEM, and Bruker XFlash 6T130 EDX Detector. Materials include carrot, TSP, silver nitrate, gold chloride, sodium borohydride, and nitroaromatic compounds.

4：Experimental Procedures and Operational Workflow:

For CDs preparation, 5 g of finely chopped carrot was refluxed with 25 mL of 100 mM TSP solution for 3 hours. The formation of CDs was confirmed by UV light irradiation and characterized using various spectroscopic and microscopic techniques. For bioimaging, bacterial cells (E. coli and S. aureus) were incubated with CDs, washed, and imaged using a fluorescence microscope. For nanoparticle preparation, CDs were added to solutions of silver nitrate or gold chloride and left for 12 hours, followed by characterization. For catalytic activity, nanoparticles were used in hydrogenation reactions with nitroaromatic compounds and sodium borohydride, monitored by UV-visible spectroscopy.

5：Data Analysis Methods:

Fluorescence and UV-visible spectra were analyzed to determine excitation/emission maxima and surface plasmon resonance. TEM images were used to assess size and morphology. FTIR, NMR, and XPS were used for functional group analysis. Kinetic data from hydrogenation reactions were fitted to a pseudo-first-order rate equation to determine rate constants.